arch/arm/rtl8721f: add ADC driver support

Wire the shared Ameba ADC driver into the RTL8721F build: add the
per-chip ameba_adc_chip.h (12 channels, CH0..CH7 external on
PA20,PA19,PA18,PA17,PA15,PA14,PA13,PA12, PINMUX function 5), the
board ADC table and registration, the adc board config, and build
glue for both cmake and make (including the fwlib RAM-layer
ameba_adc.c in ameba_board.mk). Document the ADC on the board index.

Signed-off-by: dechao_gong <dechao_gong@realsil.com.cn>
Assisted-by: Claude <noreply@anthropic.com>

Author: dcgong2917

Documentation/platforms/arm/rtl8721f/boards/rtl8721f_evb/index.rst

@@ -42,6 +42,8 @@ Supported in this NuttX port:
   on the SDK fwlib register layer
 * PWM output exposed as a ``/dev/pwm0`` character device, driven directly on
   the SDK fwlib timer register layer
+* ADC channels exposed as an ``/dev/adc0`` character device, driven directly
+  on the SDK fwlib register layer
 
 Buttons and LEDs
 ================
@@ -147,6 +149,21 @@ example::
 
     nsh> pwm -d 25 -f 1000     # 1 kHz, 25% duty on /dev/pwm0
 
+adc
+---
+
+Minimal NSH with the ADC driver and the ``adc`` example enabled (no Wi-Fi).
+The board registers its channels from a table (see
+``boards/arm/rtl8721f/rtl8721f_evb/src/rtl8721f_adc.c``): ``/dev/adc0`` samples
+CH0 on PA20 and CH1 on PA19. Edit that table -- channel numbers and the analog
+pad each is wired to -- to match a board's wiring; the external channels
+CH0..CH7 map to pads PA20,PA19,PA18,PA17,PA15,PA14,PA13,PA12 and are muxed to
+the ADC function through the SDK ROM, while internal channels carry
+``AMEBA_ADC_PIN_NC``. Every listed channel is sampled, in order, on each
+trigger. Read the channels with the example::
+
+    nsh> adc -n 1                        # one sweep of /dev/adc0
+
 nsh
 ---
 

arch/arm/src/rtl8721f/CMakeLists.txt

@@ -66,6 +66,10 @@ if(CONFIG_AMEBA_PWM)
   list(APPEND SRCS ${AMEBA_COMMON}/ameba_pwm.c)
 endif()
 
+if(CONFIG_AMEBA_ADC)
+  list(APPEND SRCS ${AMEBA_COMMON}/ameba_adc.c)
+endif()
+
 target_include_directories(arch PRIVATE ${AMEBA_COMMON})
 target_sources(arch PRIVATE ${SRCS})
 
@@ -145,6 +149,14 @@ if(CONFIG_AMEBA_PWM)
   list(APPEND AMEBA_FWLIB_SRCS ${AMEBA_SOC}/fwlib/ram_common/ameba_tim.c)
 endif()
 
+# ADC (SAR) register layer.  The ADC driver (arch/.../common/ameba/ameba_adc.c)
+# calls the fwlib ADC API; the data tables and helpers it indexes live in this
+# RAM source and must be compiled in (--gc-sections drops the unused
+# interrupt/timer-trigger helpers).
+if(CONFIG_AMEBA_ADC)
+  list(APPEND AMEBA_FWLIB_SRCS ${AMEBA_SOC}/fwlib/ram_common/ameba_adc.c)
+endif()
+
 # Silence a couple of warnings the vendored SDK sources trip under NuttX's
 # warning set, scoped to this fwlib compile only (never relaxing NuttX's own):
 # -Wno-int-conversion: the SDK passes NULL to irq_register()'s u32 "Data"

arch/arm/src/rtl8721f/Make.defs

@@ -76,6 +76,10 @@ ifeq ($(CONFIG_AMEBA_PWM),y)
 CHIP_CSRCS += ameba_pwm.c
 endif
 
+ifeq ($(CONFIG_AMEBA_ADC),y)
+CHIP_CSRCS += ameba_adc.c
+endif
+
 ############################################################################
 # Realtek RTL8721F SDK integration
 #

arch/arm/src/rtl8721f/ameba_adc_chip.h

@@ -0,0 +1,84 @@
+/****************************************************************************
+ * arch/arm/src/rtl8721f/ameba_adc_chip.h
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_ARM_SRC_RTL8721F_AMEBA_ADC_CHIP_H
+#define __ARCH_ARM_SRC_RTL8721F_AMEBA_ADC_CHIP_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Per-chip ADC wiring for RTL8721F (amebagreen2).  The shared driver
+ * (arch/arm/src/common/ameba/ameba_adc.c) includes this header to learn how
+ * many channels the converter can list, the crossbar pad-mux code that turns
+ * a pad into an analog input, and the peripheral-clock masks.  A port to
+ * another Ameba chip supplies a same-named header on the chip include path;
+ * the shared driver is never edited -- it reads only the macros below, and
+ * it drives the ADC through the SDK fwlib API, which internally selects the
+ * secure/non-secure register alias (via TrustZone_IsSecure()), so no
+ * register base appears here at all.
+ *
+ * Values below are taken from the amebagreen2 fwlib headers (verified, not
+ * guessed): PINMUX_FUNCTION_ADC=5 (ameba_pinmux.h), ADC_IRQ=42
+ * (ameba_vector_table.h), APBPeriph_ADC and APBPeriph_ADC_CLOCK both
+ * bit30|bit23 (sysreg_lsys.h).  RTL8721F does not route the ADC through the
+ * cap-touch/CTC block, so no second clock domain is needed and
+ * AMEBA_ADC_AUXCLK_* stay undefined.
+ *
+ * External channels CH0..CH7 map to pads PA20,PA19,PA18,PA17,PA15,PA14,
+ * PA13,PA12 (from ameba_adc.h ADC_CHx_PIN); CH8..CH10 and CH14 are fixed
+ * internal channels with no pad.  The 16-bit conversion word (channel id in
+ * [19:16], data in [15:0]) is identical on every current Ameba chip, so the
+ * driver extracts it directly and no macro is needed here.
+ */
+
+#define AMEBA_ADC_NCHAN           12    /* ADC_CH_NUM: CH0..CH7 ext, rest int  */
+#define AMEBA_ADC_MAXLIST         16    /* Channel-switch list depth (Cvlist)  */
+#define AMEBA_ADC_PINMUX_FID      5     /* PINMUX_FUNCTION_ADC                  */
+#define AMEBA_ADC_IRQ             42    /* ADC_IRQ (unused by this polling drv) */
+
+/* sizeof(fwlib ADC_InitTypeDef): OpMode/CvlistLen/Cvlist[16] then
+ * RxThresholdLevel/SpecialCh/SamplePeriodUs(u16) -> 22 bytes.  The shared
+ * driver sizes its stack mirror from this so ADC_StructInit() cannot
+ * overflow it.
+ */
+
+#define AMEBA_ADC_INIT_SIZE       22
+
+/* APBPeriph_ADC (function) and APBPeriph_ADC_CLOCK masks.  Equal on this
+ * chip; both set the bit30 group selector and bit23 for the LP ADC block.
+ * RTL8721F needs no second clock domain, so AMEBA_ADC_AUXCLK_* are left
+ * undefined (amebalite/amebasmart define them to gate APBPeriph_CTC too).
+ */
+
+#define AMEBA_ADC_APBPERIPH       (((uint32_t)1 << 30) | ((uint32_t)1 << 23))
+#define AMEBA_ADC_APBPERIPH_CLK   (((uint32_t)1 << 30) | ((uint32_t)1 << 23))
+
+#endif /* __ARCH_ARM_SRC_RTL8721F_AMEBA_ADC_CHIP_H */

arch/arm/src/rtl8721f/ameba_board.mk

@@ -176,6 +176,14 @@ ifeq ($(CONFIG_AMEBA_PWM),y)
 AMEBA_FWLIB_SRCS += $(AMEBA_SOC)/fwlib/ram_common/ameba_tim.c
 endif
 
+# ADC (SAR) register layer.  The ADC driver
+# (arch/.../common/ameba/ameba_adc.c) calls the fwlib ADC API; the data tables
+# and helpers it indexes live in this RAM source and must be compiled in
+# (--gc-sections drops the unused interrupt/timer-trigger helpers).
+ifeq ($(CONFIG_AMEBA_ADC),y)
+AMEBA_FWLIB_SRCS += $(AMEBA_SOC)/fwlib/ram_common/ameba_adc.c
+endif
+
 # -Wno-int-conversion: the vendored SDK passes NULL to irq_register()'s u32
 # "Data" (interrupt context) argument in many places -- an intentional
 # NULL-as-context idiom.  Silence -Wint-conversion for the SDK fwlib sources

boards/arm/rtl8721f/rtl8721f_evb/configs/adc/defconfig

@@ -0,0 +1,53 @@
+#
+# This file is autogenerated: PLEASE DO NOT EDIT IT.
+#
+# You can use "make menuconfig" to make any modifications to the installed .config file.
+# You can then do "make savedefconfig" to generate a new defconfig file that includes your
+# modifications.
+#
+# CONFIG_DEBUG_WARN is not set
+CONFIG_AMEBA_ADC=y
+CONFIG_ARCH="arm"
+CONFIG_ARCH_BOARD="rtl8721f_evb"
+CONFIG_ARCH_BOARD_RTL8721F_EVB=y
+CONFIG_ARCH_CHIP="rtl8721f"
+CONFIG_ARCH_CHIP_RTL8721F=y
+CONFIG_ARCH_INTERRUPTSTACK=2048
+CONFIG_ARCH_STACKDUMP=y
+CONFIG_ARMV8M_SYSTICK=y
+CONFIG_BUILTIN=y
+CONFIG_DEBUG_ASSERTIONS=y
+CONFIG_DEBUG_FEATURES=y
+CONFIG_DEBUG_FULLOPT=y
+CONFIG_DEBUG_SYMBOLS=y
+CONFIG_DEFAULT_TASK_STACKSIZE=4096
+CONFIG_EXAMPLES_ADC=y
+CONFIG_EXAMPLES_ADC_GROUPSIZE=2
+CONFIG_EXAMPLES_ADC_NSAMPLES=1
+CONFIG_EXAMPLES_ADC_SWTRIG=y
+CONFIG_EXAMPLES_HELLO=y
+CONFIG_FS_PROCFS=y
+CONFIG_FS_TMPFS=y
+CONFIG_IDLETHREAD_STACKSIZE=4096
+CONFIG_INIT_ENTRYPOINT="nsh_main"
+CONFIG_LIBC_MEMFD_ERROR=y
+CONFIG_MM_DEFAULT_ALIGNMENT=32
+CONFIG_NSH_BUILTIN_APPS=y
+CONFIG_NSH_FILEIOSIZE=512
+CONFIG_NSH_READLINE=y
+CONFIG_PREALLOC_TIMERS=4
+CONFIG_RAM_SIZE=401408
+CONFIG_RAM_START=0x20006000
+CONFIG_RR_INTERVAL=200
+CONFIG_SCHED_HPWORK=y
+CONFIG_SCHED_HPWORKPRIORITY=192
+CONFIG_SCHED_LPWORK=y
+CONFIG_STACK_COLORATION=y
+CONFIG_START_DAY=16
+CONFIG_START_MONTH=6
+CONFIG_START_YEAR=2026
+CONFIG_SYSTEM_NSH=y
+CONFIG_SYSTEM_NSH_STACKSIZE=2500
+CONFIG_TIMER=y
+CONFIG_TIMER_ARCH=y
+CONFIG_USEC_PER_TICK=1000

boards/arm/rtl8721f/rtl8721f_evb/src/CMakeLists.txt

@@ -42,13 +42,18 @@ if(CONFIG_AMEBA_PWM)
   list(APPEND SRCS rtl8721f_pwm.c)
 endif()
 
+if(CONFIG_AMEBA_ADC)
+  list(APPEND SRCS rtl8721f_adc.c)
+endif()
+
 target_sources(board PRIVATE ${SRCS})
 
 if(CONFIG_AMEBA_GPIO
    OR CONFIG_AMEBA_UART
    OR CONFIG_AMEBA_I2C
    OR CONFIG_AMEBA_SPI
-   OR CONFIG_AMEBA_PWM)
+   OR CONFIG_AMEBA_PWM
+   OR CONFIG_AMEBA_ADC)
   # The board pin tables pull in the shared drivers' public headers from
   # arch/arm/src/common/ameba/, not on the default board include path.
   target_include_directories(board

boards/arm/rtl8721f/rtl8721f_evb/src/Makefile

@@ -44,10 +44,14 @@ ifeq ($(CONFIG_AMEBA_PWM),y)
 CSRCS += rtl8721f_pwm.c
 endif
 
+ifeq ($(CONFIG_AMEBA_ADC),y)
+CSRCS += rtl8721f_adc.c
+endif
+
 # The board pin tables pull in the shared drivers' public headers from
 # arch/arm/src/common/ameba/, which is not on the default board include path.
 
-ifneq ($(CONFIG_AMEBA_GPIO)$(CONFIG_AMEBA_UART)$(CONFIG_AMEBA_I2C)$(CONFIG_AMEBA_SPI)$(CONFIG_AMEBA_PWM),)
+ifneq ($(CONFIG_AMEBA_GPIO)$(CONFIG_AMEBA_UART)$(CONFIG_AMEBA_I2C)$(CONFIG_AMEBA_SPI)$(CONFIG_AMEBA_PWM)$(CONFIG_AMEBA_ADC),)
 CFLAGS += ${INCDIR_PREFIX}$(TOPDIR)$(DELIM)arch$(DELIM)arm$(DELIM)src$(DELIM)common$(DELIM)ameba
 endif
 

boards/arm/rtl8721f/rtl8721f_evb/src/rtl8721f_adc.c

@@ -0,0 +1,90 @@
+/****************************************************************************
+ * boards/arm/rtl8721f/rtl8721f_evb/src/rtl8721f_adc.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/param.h>
+#include <syslog.h>
+#include <errno.h>
+
+#include "ameba_gpio.h"
+#include "ameba_adc.h"
+#include "rtl8721f_rtl8721f_evb.h"
+
+#ifdef CONFIG_AMEBA_ADC
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* Channels sampled on /dev/adc0 and the analog pad each is wired to.  The
+ * external channels CH0..CH7 map to pads PA20,PA19,PA18,PA17,PA15,PA14,
+ * PA13,PA12; this board exposes CH5 on PA14 and CH6 on PA13.  Any external
+ * channel can be listed here; internal channels would carry
+ * AMEBA_ADC_PIN_NC.
+ */
+
+static const uint8_t g_adc_channels[] =
+{
+  5,                 /* ADC_CH5 */
+  6,                 /* ADC_CH6 */
+};
+
+static const uint8_t g_adc_pins[] =
+{
+  AMEBA_PA(14),      /* CH5 -> PA14 */
+  AMEBA_PA(13),      /* CH6 -> PA13 */
+};
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: rtl8721f_adc_initialize
+ *
+ * Description:
+ *   Register the board's ADC channels at /dev/adc0.
+ *
+ ****************************************************************************/
+
+int rtl8721f_adc_initialize(void)
+{
+  int ret;
+
+  ret = ameba_adc_register("/dev/adc0", g_adc_channels, g_adc_pins,
+                           nitems(g_adc_channels));
+  if (ret < 0)
+    {
+      syslog(LOG_ERR,
+             "ERROR: ameba_adc_register(/dev/adc0) failed: %d\n", ret);
+      return ret;
+    }
+
+  return OK;
+}
+
+#endif /* CONFIG_AMEBA_ADC */

boards/arm/rtl8721f/rtl8721f_evb/src/rtl8721f_bringup.c

@@ -184,6 +184,16 @@ int rtl8721f_bringup(void)
     }
 #endif
 
+#ifdef CONFIG_AMEBA_ADC
+  /* Register the board's ADC channels at /dev/adc0. */
+
+  ret = rtl8721f_adc_initialize();
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "ERROR: rtl8721f_adc_initialize failed: %d\n", ret);
+    }
+#endif
+
   IPC_patch_function(rtos_critical_enter, rtos_critical_exit,
                      AMEBA_RTOS_CRITICAL_SEMA);
   IPC_SEMDelayStub(rtos_time_delay_ms);